Building with foam cored ribs and method

ABSTRACT

A building includes an inflatable form having an interior surface bounding a chamber. A stabilizing layer of polymeric foam or cementitious material is disposed on the interior surface of the inflatable form. At least one support layer of cementitious material is disposed on the interior surface of the stabilizing layer. Finally, one or more ribs project from the interior surface of the at least one support layer. Each rib includes a core of polymeric foam and a layer of cementitious material disposed over the core.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/241,328, filed Sep. 11, 2002, which is incorporated herein byspecific reference.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to buildings and, more specifically,enlarged domed buildings having reinforcing ribs formed on the insidethereof.

2. The Relevant Technology

The use of freestanding dome shaped buildings is becoming increasinglypopular. In contrast to conventional rectangular buildings, dome shapedbuildings can be formed relatively quickly and have a large interiorspace which is free from obstructions such as columns or other supports.Conventional dome structures are formed by inflating a flexible liner.One or more reinforced layers of shotcrete are formed on the interiorsurface of the liner. Once the shotcrete is cured, the dome isself-supporting.

One of the historical shortcomings in the formation of dome structuresis the inability to continue to construct larger sized domes usingconventional methods. That is, prior to setting of the shotcrete, thedome structure are largely supported by an applied internal airpressure. As the dome increases in size, however, the thickness of theshotcrete layer must also increase to provide the required, structuralstrength. As the amount of shotcrete increases, however, the weight onthe dome also increases until the weight of the shotcrete is greaterthan the applied air pressure to support it. This can result incatastrophic failure of the dome structure during assembly.

Attempts to further increase the supporting air pressure within the domehave simply resulted in failure of the liner, such as by rupture.Attempts have also been made to increase the structural strength of suchdomes by forming solid concrete ribs on the interior surface of thedome. Such solid concrete ribs, however, are difficult to form and addsignificant additional weight to the dome.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will now be discussed withreference to the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope.

FIG. 1 is a perspective view of a domed building;

FIG. 2 is a cross section side view of a portion of the building shownin FIG. 1 in a partially assembled state;

FIG. 3 is a perspective view of an inflated form mounted on a footing;

FIG. 4 is a perspective view of a hanger;

FIG. 5 is a cross sectional side view of a partially assembled buildinghaving reinforcing line mounted against a stabilizing layer;

FIG. 6 is a cross sectional side view of a partially assembled buildingshowing an alternative placement of reinforcing line;

FIG. 7 is a perspective view of one embodiment of a line hanger;

FIG. 8 is a perspective view of an alternative embodiment of a linehanger;

FIG. 9 is a cross sectional side view of a partially assembled buildingshowing hangers and retention line embedded within a stabilizing layer;

FIG. 10 is a perspective view of a building showing a retention assemblymounted on the exterior surface thereof;

FIG. 11 is a cross sectional side view of partially assembled buildingshowing a reinforcing mat mounted on the interior surface of astabilizing layer;

FIG. 12 is a cross section side view of the building shown in FIG. 11with a support layer covering the reinforcing mat;

FIG. 13 is a cross sectional side view of the building shown in FIG. 12with a second support layer;

FIG. 14 is a cross sectional side view of a building having ribs formedthereon;

FIG. 15 is a cross sectional side view of a partially assembled rib;

FIG. 16 is a partially cut away view of a building showing stackedblocks forming a core of a rib shown in FIG. 15;

FIG. 17 is a cross sectional side view of the rib shown in FIG. 15 in acompleted state;

FIG. 18 is a cross sectional side view of a boundary wall of a buildingwherein a retention assembly as been mounted on the exterior surfacethereof;

FIG. 19 is a cross sectional side view of a boundary wall having a ribform mounted thereon;

FIG. 20 is a perspective view of the form shown in FIG. 19;

FIG. 21 is a cross sectional side view of the completed rib shown inFIG. 19;

FIGS. 22-25 are cross sectional side views show sequential steps in themanufacture of an alternative rib configuration; and

FIG. 26 is a top plan view of a building having compound curves.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

I. Introduction

Depicted in FIG. 1 is one embodiment of an inventive building 10incorporating features of the present invention. In general, building 10comprises an annular footing 12 on which a dome shaped boundary wall 14is formed. Boundary wall 14 has an exterior surface 16 and an interiorsurface 18. Interior surface 18 bounds a chamber 20. Chamber 20 isaccessible through an entrance 19 which extends through boundary wall 14and is selectively blocked by doors 21. If desired, a shelter can beformed on the exterior of building 10 so as to cover entrance 19.

Briefly stated, in one embodiment building 10 is constructed by firstlaying footing 12. With reference to FIG. 2, an inflatable form 22 isthen secured to the exterior surface of footing 12 in air-tight relationtherewith. Form 22 is then inflated to a first air pressure. Once form22 is inflated, one or more stabilizing layers is applied against aninterior surface of form 22. An example of a suitable material for thestabilizing layer is a polymeric foam which can be sprayed onto form 22.

In one embodiment of the present invention, means are provided forreinforcing form 22 so that form 22 can withstand higher internal airpressures without failure. One example of the means for reinforcing form22 comprises one or more layers of reinforcing line embedded laterally,longitudinally, and/or otherwise within the stabilizing layer.Alternatively or in combinations therewith, the means for reinforcingform 22 comprises a plurality of interconnected retention lines securedover the exterior surface of form 22.

Mounted on the interior surface of the one or more stabilizing layers isa reinforcing mat which typically comprises interconnecting strands ofrebar. One or more support layers are then applied over the interiorsurface of the stabilizing layer such that the reinforcing mat isembedded therein. In one embodiment, the one or more support layers istypically formed of a cementitious material such as concrete orshotcrete.

Although not required, in one embodiment an array of ribs is formed onthe interior surface of the support layer. As discussed below in greaterdetail, the ribs can have a variety of different configurations and canbe positioned in a variety of different orientations. Finally, ifdesired, a finish layer can be applied over the support layer and ribs.

Depending on the size and configuration of building 10, the amount ofinternal air pressure within chamber 20 can be selectively increased atvarious stages during development. In part, the increased air pressuresupports the building as the various layers are applied and harden toobtain their final strength.

The inventive building process enables the safe manufacture of domeshaped buildings on a significantly larger scale than what was enabledunder the prior art. Outlined below is a detailed description ofexamples of alternative methods for manufacturing buildingsincorporating domed features. Although the methods are primarilydiscussed with reference to the manufacture of the annular domed shapedbuilding 10 shown in FIG. 1, it is appreciated that substantially thesame methods can be used in the manufacture of other shaped buildingswhich incorporate dome features. Examples of the shapes of such otherbuildings will also be discussed below. Furthermore, it is alsoappreciated that substantially the same methods can be used in themanufacture of building which do not incorporate a dome feature.

II. Footing

Footing 12 provides a foundation for building 10 and defines the outerperimeter thereof. As depicted in FIG. 2, footing 12 comprises anoutwardly extending base portion 38 and a wall portion 40 upwardlyextending therefrom. Wall portion 40 has an interior surface 39, a topsurface 41, and an exterior surface 42. A plurality of spaced apartbolts 44 are partially embedded within wall portion 40 so as to radiallyoutwardly project from exterior surface 42 thereof. In one embodiment,bolts 44 are disposed about every 25 cm to about every 100 cm aroundfooting 12. Other spacing can also be used based on building parameters.As will be discussed below in greater detail, bolts 44 are used tosecure inflatable form 22 to footing 12.

Also partially embedded within footing 12 so as to upwardly project fromtop surface 41 of wall portion 40 are a plurality of spaced apartreinforcing rods 31. As will be discussed below in greater detail,reinforcing rods 31 are used to facilitate a rigid connection betweenfooting 12 and boundary wall 14. Reinforcing rods 31 typically compriseconventional steel rebar although other conventional reinforcingmaterials can also be used. Reinforcing rods 31 are typically placedabout every 25 cm to 100 cm, although other spacing can also be usedbased on building parameters.

Footing 12 is typically comprised of poured concrete having reinforcingembedded therein. In the embodiment shown, footing 12 has a invertedsubstantially T-shaped transverse cross section. In alternativeembodiments, footing 12 can have any desired transverse cross sectionthat satisfies the building parameters. For example, footing 12 shouldbe dimensioned to withstand frost conditions and be designed inaccordance with the size of the building and the weight bearing capacityof the underlying soil.

As previously mentioned, footing 12 outlines the perimeter or footprintfor building 10. In one embodiment, footing 12 is placed in a circularpath. In alternative embodiments, as will be discussed below with regardto final building designs, footing 12 can also be placed in a variety ofother patterns such as oval, polygonal, irregular, or combinationsthereof.

In one embodiment, wall portion 40 of footing 12 may be placedcompletely under ground or project a few feet above the ground surface.In alternative embodiments, wall portion 40 can vertically extend so asto form a wall around the base of building 10. For example, wall portion40 can have a height in a range between about 2 meters to about 8 metersor any other desired height. In this embodiment, entrance 19 to building10 can be formed through wall portion 40.

It is generally desirable that prior to securing inflatable form 22 tofoundation 12, all equipment that will be used in the construction ofbuilding 10 and which is too large to be moved into the building areathrough an access, to be described below, be placed within the area ofchamber 20 bounded by footing 12. Once the equipment is positioned, form22 is spread over the equipment and secured to footing 12.

III. Inflatable Form

As depicted in FIGS. 2 and 3, inflatable form 22 comprises a pluralityof flexible, sheet-like panels that have been sewn, seamed, or otherwisesecured together such that when mounted on footing 12 and inflated, form22 forms a substantially dome-shaped surface. Alternatively, inflatableform 22 can be configured so that at least a portion of the form forms adome shaped configuration or so that the form does not include a domeshaped configuration. For example, inflatable form 22 can form a box,cone, or other configuration.

Form 22 has an interior surface 23 and an exterior surface 25 which eachextend to an outer peripheral edge 46. In one embodiment, form 22 iscomprised of a lightweight gas and liquid impermeable flexible sheet.The sheet can be formed from a cross laminate plastic, a reinforcedplastic coated fabric, such as a polyvinyl chloride impregnated Dacron,or any other suitable material. Furthermore, form 22 can be formed ofone or more layers of material. As will become more apparenthereinbelow, form 22 may be reusable or may be left in place afterforming building structure 10.

In one embodiment of the present invention, means are provided forsecuring form 22 to footing 12 in a substantially air tight engagement.By way of example and not by limitation, a loop 47 is formed atperipheral edge 46 of form 22. A line 48, such as a cord or cable, ispasses through loop 47 so as to extend along peripheral edge 46. Inalternative embodiments, line 48 can be secured to peripheral edge 46 byuse of any of a number of conventional techniques. Peripheral edge 46having line 48 coupled therewith is positioned against exterior surface42 of footing 12 so that form 22 covers the area bounded by footing 12.

A sheathed clamping cable 50 is then positioned against exterior surface25 of form 22 above line 48. Clamping cable 50 is tensioned in acontinuous loop so as to bias form 22 against exterior surface 42 offooting 12, thereby preventing line 48 from passing between clampingcable 50 and footing 12. In one embodiment, clamping cable 50 isdisposed tightly against line 48.

Once clamping cable 50 is tensioned, a plurality of elongated clamps 52are mounted to footing 12. Each clamp 52 has a substantially C-shapedtransverse cross section with spaced apart apertures 51 formed along thelength thereof. Clamps 52 are mounted against footing 12 so as to coverline 48 and clamping cable 50 with bolts 44 extending through apertures51. A nut 54 is threaded onto the free end of each bolt 44 so as tosecurely bias each clamp 52 against footing 12. Clamps 52 thus preventclamping cable 50 and/or line 48 from sliding off of footing 12 duringthe inflation of form 22.

One alternative embodiment of the means for securing form 22 to footing12 is depicted in FIG. 2 of U.S. Pat. No. 4,324,074. Disclosure withinthe '074 patent relating to securing the form to the footing is herebyincorporated by specific reference. It will be appreciated that otherembodiments also exist for securing form 22 to footing 12. By way ofexample and not by limitation, bolts, hooks, and other types offasteners can be used to directly secure form 22 to footing 12.

As depicted in FIG. 3, an air port 55 is formed on form 22. A duct 56provides sealed communication between air port 55 and a blower 57.During operation, blower 57 is activated causing air from thesurrounding environment to be blown through duct 56 and air port 55 soas to inflate form 22. As a result of the inflation of form 22, chamber20 is bounded therein.

Blower 57 is used to inflate form 22 so that a first air pressure isformed therein. In one embodiment, the first pressure is in a rangebetween about ½inch H₂O to about 2 inches H₂O of static pressure. Inother embodiments depending on the weight and size of form 22, otherpressures may also be used.

To enable access to chamber 20, a temporary access 32 is formed on form22 adjacent to air port 55. Mounted in substantially sealedcommunication with temporary access 32 is an air lock 33. In oneembodiment, air lock 33 simply comprises a structure having a firstdoorway, a second doorway, and a compartment formed therebetween. Aspeople enter and exit chamber 20 through air lock 33, only one of thefirst and second doorways is open at a time. As a result, air withinchamber 20 cannot significantly escape through air lock 33. The pressurewithin chamber 20 is thus maintained within a desired safety range.

As previously discussed, where wall portion 40 of footing 12 upwardlyextends to form a perimeter wall, it is also appreciated that temporaryaccess 32 and/or air port 55 can be formed through wall portion 40 asopposed to through form 22. When building structure 10 is completed, airport 55 and/or temporary access 32 may eventually form entrance 19 or awindow.

After form 22 is inflated, entrances, windows, and all other openingsthat are to be present on building 10 are marked on interior surface 23of inflated form 22. In one embodiment, the various layers of rebarand/or other select layers can be applied so as not to cover the markedopenings. As a result, the openings can be more easily cut out onceconstruction of building 10 is completed.

IV. Stabilizing Layer

Returning to FIG. 2, after inflating form 22 a stabilizing layer 24 isapplied to interior surface 23 of form 22. Stabilizing layer 24 isgenerally comprised of a polymeric foam. As used in the specificationand appended claims, the term “polymeric foam” is intended to includeall polymeric materials that have been expanded in some way so as toform a foam. Examples of polymeric foams include polyurethane foam,Styrofoam, and other conventional expandable polymeric foams. Thepolymeric foam can also comprise additives such as fillers, fibers, orother additives which affect properties such as strength, expansion,setting, finish, and the like. The polymeric foam can be applied throughconventional spraying techniques or other conventional processes.Likewise, the polymeric foam can be applied in prefabricatedconfigurations. One common example of a polymeric foam used in themanufacture of stabilizing layer 24 is 1½lb/ft³ to 2 lb/ft³ polyurethanefoam which is sprayed onto form 22. In other embodiments, it is alsoappreciated that non-polymeric materials, such as cementitiousmaterials, adhesives, or any other types of materials that can beapplied and then set to provide structural support, can also be used forstabilizing layer 24.

Although not required, in one embodiment to help ensure that stabilizinglayer 24 initially secures to interior surface 23 of form 22 asstabilizing layer 24 is initially applied thereto, a bonding agent isapplied in a layer over interior surface 23 of form 22. In oneembodiment, the bonding agent comprises an acrylic latex bonding agentsuch as V-COAT available from Diamond Vogel Paint out of Orange City,Iowa. In other embodiments, the bonding agent can simply comprise asrewettable bonding agent that has adhesive properties when hydrated soas to help stick stabilizing layer 24 to form 22. Use of the bondingagent is most applicable when stabilizing layer 24 is comprised of acementitious material.

In part, stabilizing layer 24 functions to initially stabilize form 22and provided a basis on which additional layers can be built. Althoughnot required, the material for stabilizing layer 24 can be selected soas to have insulative properties. In this embodiment, stabilizing layer24 forms an insulation barrier which helps control the temperaturewithin chamber 20 and prevent the formation of condensation on theinterior surface of building 10 bounding chamber 20. The material forstabilizing layer 24 can also be selected so that form 22 can be removedafter or during the development of building 10. Alternatively, thematerial can be selected so that stabilizing layer 24 permanentlyadheres to form 22.

Depending on the engineering design of building 10, stabilizing layer 24can be formed as a single layer from a single application.Alternatively, stabilizing layer 24 can be comprised of multipleoverlapping sub-layers of the same or different materials. For example,stabilizing layer 24 comprises a first stabilizing sub-layer 24 a and asecond stabilizing sub-layer 24 b. First stabilizing sub-layer 24 a andsecond stabilizing sub-layer 24 b combine to form a single,substantially inseparable stabilizing layer 24. In yet other embodiment,it is appreciated that stabilizing layer 24 may not be required at all.

Stabilizing layer 24 is applied to inner surface 23 of inflated form 22by initially spraying first stabilizing sub-layer 24 a having athickness in a range between about 1 cm to about 5 cm with about 1 cm toabout 3 cm being more common. A plurality of spaced apart hanger 58 arethen mounted on sub-layer 24 a.

As depicted in FIG. 4, each hanger 58 comprises a planar base plate 60having a front side 62 and an opposing back side 64. An elongated hangerrod 66 centrally projects from front side 62. Each side of base plate 60typically has a surface area in a range between about 1 square inch toabout 4 square inches with about 2 square inches being more common. Baseplate 60 is generally made of a suitable strength metallic sheet such asgalvanized sheet steel. A plurality of holes 68 may be formed throughbase plate 60 so as to reduce the overall weight of each hanger 58 andallow communication therethrough. In an alternative embodiment, baseplate 60 can be formed of other materials such as plastic, composites,or other types of metals.

In one embodiment of the present invention, means are provided forsecuring hangers 58 to stabilizing sub-layer 24 a. By way of example andnot by limitation, outwardly projecting from back side 64 of base plate60 are a plurality of spaced apart barbs 70. Barbs 70 are configuredsuch that hangers 58 can initially be secured to stabilizing sub-layer24 a by simply pushing barbs 70 into stabilizing sub-layer 24 a untilbase plate 60 rests against stabilizing sub-layer 24 a.

In alternative embodiments of the means for securing hangers 58, barbs70 can be formed with outwardly engaging teeth. In other embodiments,barbs 70 can have a spiral configuration or be replaced with hooks,spikes, adhesive pads, adhesive, and other conventional fasteners.Furthermore, it is appreciated that hangers 58 can be replaced withother hangers or ties used in conventional building practices.

Each hanger rod 66 is generally made of a flexible metal, such asaluminum, and is secured in a generally normal relationship to the planeof the associated base plate 60. Hangers 58 are secured to firststabilizing sub-layer 24 a such that hanger rods 66 project inwardlyfrom first stabilizing sub-layer 24 a in substantially normal relationthereto.

Referring again to FIG. 2, once hangers 58 are secured to firststabilizing sub-layer 24 a, a second stabilizing sub-layer 24 b issprayed over stabilizing sub-layer 24 a so as to embed base plate 60 ofhangers 58 therebetween. The now complete stabilizing layer 24 typicallyhas a thickness in a range between about 5 cm to about 15 cm. Thethickness of stabilizing layer 24 in part depends on the desired amountof insulation. In general, insulative properties increase as stabilizinglayer 24 gets thicker. It will be appreciated that first stabilizingsub-layer 24 a and second stabilizing sub-layer 24 b may have the samethickness or have different thicknesses. In one example, firststabilizing sub-layer 24 a is about 5 cm thick and second stabilizingsub-layer 24 b is about 5 cm thick. In another example, firststabilizing sub-layer 24 a is about 5 cm thick and second stabilizingsub-layer 24 b is about 8 cm thick. Additionally, it will be appreciatedthat first stabilizing sub-layer 24 a and second stabilizing sub-layer24 b may be comprised of the same material or different material. Othercombinations may also be employed depending on the engineering designand construction needs of building structure 10.

Each hanger rod 66 of hangers 58 has a predetermined length. As such,during the application of second stabilizing sub-layer 24 b, theoperator is able to visually observe the depth of stabilizing sub-layer24 b being applied through observing the build-up depth along the lengthof hanger rods 66. Additionally, the relatively thin hanger rods 66enable a uniform spraying of polymeric foam about hanger rods 66 withoutimpairing uniformity of density or layer thickness of the foam. Hangerrods 66 are made long enough to extend outwardly from the completedstabilizing layer 24 a distance in a range between about 8 cm to about15 cm, although other dimensions can also be used. It is alsoappreciated that markings can be formed along the length of hanger rods66 so as to assist in forming stabilizing sub-layer 24 b to a desireddepth.

As a result of base plate 60 of hangers 58 being at least partiallyembedded within stabilizing layer 24, a reinforcing mat, as discussedbelow, can now be secured to hangers 58 without pulling hanger 58 off ofstabilizing layer 24. It is also appreciated that in other embodimentsbase plate 60 of hangers 58 can be sufficiently secured directly to aninterior surface 29 of stabilizing layer 24 so that base plate 60 neednot be embedded within stabilizing layer 24.

V. Reinforcing Inflatable Form

As stabilizing layer 24 and/or other layers, as discussed below, areformed inward of inflated form 22, the weight of building 10 increases.In some embodiments, depending on the size and configuration of building10, it is desirable to incrementally increase the air pressure withinchamber 20 produced by blower 57 so as to support the increased weightload of the building while the various layers are applied and/or set toreach their supporting strength.

The air pressure, however, cannot be increased beyond the pressurelimits of form 22 or, where applicable, the combination of form 22 andstabilizing layer 24. Accordingly, to enable the air pressure withinchamber 20 to be safely increased, means are provided for reinforcingform 22 and/or support layer 24. By way of example and not bylimitation, in one embodiment the means for reinforcing comprisesreinforcing line embedded within stabilizing layer 24. In an alternativeembodiment, the means for reinforcing comprises a retention assemblysecured over form 22. The reinforcing line and retention assembly areconfigured to absorb at least a portion of the increased pressure loadapplied to form 22 and/or stabilizing layer 24.

A. Reinforcing Line

Depicted in FIG. 5, reinforcing line 72 is mounted on an interiorsurface 27 of first stabilizing sub-layer 24 a. Reinforcing line 72 canbe mounted prior to, simultaneously with, or following the securing ofhangers 58 to first stabilizing sub-layer 24 a. In one embodiment,reinforcing line 72 typically comprises wire, cable, cord, plastic line,rope, webbing, or other types of flexible line having sufficient tensilestrength to withstand the force produced by the air pressure withinchamber 20. In one embodiment, reinforcing line has a tensile strengthin a range between about 20,000 psi to about 200,000 psi.

Reinforcing line 72 can comprise one or more strands and can bepositioned in any desired orientation, such as horizontal, vertical,spiral, sloped, and combinations thereof, at any desired spacing. Forexample, depicted in FIG. 5, reinforcing line 72 comprises a continuousstrand 72 a spirally secured around interior surface 27 of firststabilizing sub-layer 24 a so as to extend from footing 12 up to the topof domed building 10. Strand 72 a can be replaced with discretehorizontally disposed loops.

Furthermore, in place of or in conjunction with spirally wound strand 72a, reinforcing line 72 comprises strands 72 b which are verticallydisposed between footing 12 and the top of building structure 10. Forexample, strand 72 b comprises either discrete strands or a continuousstrand of reinforcing line 72 that extends from footing 12 on one sideof building structure 10, over the central top of building structure 10,and then back to footing 12 on the opposing side thereof. Conventionalconcrete anchors can be used to secure reinforcing line 72 to footing12.

In one embodiment as shown in FIG. 6, it is desirable to form anenlarged opening 78 through the top of building 10 once building 10 iscompleted. Opening 78 can be used to feed material into chamber 20 orreceive an plenum tube. Where opening 78 is to be formed on building 10,staggered loops 72 c of either discrete or continuous strands ofreinforcing line 72 can extend up from footing 12 to a location adjacentto opening 78 and then loop back to a spaced apart location on footing12.

Since the surface area of the top portion of building 10 is smaller thanthe surface area of the base portion thereof, continuous or discretestrands 72 d of reinforcing line 72 need only extend a portion of thevertical distance to the location of opening 78. It will be appreciatedthat reinforcing line 72 can be overlaid and crisscrossed so as to beconfigured in any desired pattern. The spacing between adjacent loops orstrands of reinforcing line 72 depends on the size and configuration ofbuilding 10. In one embodiment, the spacing is in a range between about15 cm to about 50 cm on-center, although other spacing can also be used.Although not required, in one embodiment reinforcing line 72 or sectionsthereof can be tensioned at the time of placement in a range betweenabout 15 cm to about 125 cm.

Reinforcing line 72 can initially be secured to stabilizing sub-layer 24a by simply being disposed beneath base plate 60 of hangers 58.Alternatively, specifically designed line hangers can be used. Forexample, as depicted in FIGS. 5 and 7, is a first embodiment of a linehanger 79. Line hanger 79 comprises a plate 80 having a front side 82and a back side 84. Projecting from back side 84 of plate 80 are aplurality of spaced apart barbs 85. Barbs 85 are configured to be pushedinto stabilizing sub-layer 24 a so as to secure plate 80 thereto. Inalternative embodiments, barbs 85 can be replaced with the alternativesas previously discussed with regard to barbs 70 on hangers 58.

In one embodiment of the present invention, means are provided forsecuring line 72 to front side 82 of plate 81. By way of example and notby limitation, projecting from front side 82 of plate 81 two spacedapart securing arms 86. Arms 86 face in opposing directions so that line72 can be captured therebetween. In one embodiment, arms 86 can beflexible to selectively fold over line 72 while in other embodiments,arms 86 are rigid so that line 72 must be feed below arms 86. In otherembodiments, arms 86 can be replaced with a clamp, clip, or any othertype of conventional fastener for securing line 72 to plate 81. Plate 80is formed of a relatively thin metal such that securing arms 86 can bestamped out by well-known machining processes. It will be appreciatedthat hangers 58 may be configured to provide the function of both hanger58 and line hanger 79 by adding arms 86 to plate 60 of hanger 58.

Depicted in FIGS. 5 and 8 is an alternative embodiment of a line hanger87. Line hanger 87 comprises a shaft 89. A hook 88 is located at one endof shaft 89 and is configured to receive and hold reinforcing line 72.In alternative embodiments, hook 88 can be replaced with a clip, clamp,or other conventional types of fasteners. Located at the opposing end ofshaft 89 are a plurality of outwardly projecting barbs 92. By securingreinforcing line 72 within hook 88 and pushing barbs 92 into stabilizingsub-layer 24 a, reinforcing line 72 is secured to stabilizing sub-layer24 a.

As depicted in FIG. 9, once reinforcing line 72 is secured tostabilizing sub-layer 24 a, stabilizing sub-layer 24 b is applied oversub-layer 24 a, reinforcing line 72 and the various line hangers,thereby securely embedding reinforcing line 72 within stabilizing layer24. In this configuration, as the air pressure within chamber 20 isincreased, the force produced by the air pressure is at least partiallycarried by reinforcing line 72. As a result, the air pressure withinchamber 20 can be increased to support the load produced by added layerswith minimal risk of failure of form 22.

In an alternative it is appreciated that reinforcing line 72 need not beembedded within stabilizing layer 24 but can merely be secured tointerior surface 29 of stabilizing layer 24. In other embodiments,stabilizing layer 24 can comprises three or more sub-layers withdifferent elements being disposed at different sub-layers. For example,in one embodiment hangers 58 are secured to first stabilizing sub-layer24 a of stabilizing layer 24 as previously discussed. Second stabilizingsub-layer 24 b is then applied over hangers 58 to secure hangers 58 inplace. Reinforcing line 72 is then secured to second stabilizingsub-layer 24 b by the use of line hangers as discussed above. Finally, athird stabilizing sub-layer 24 c (not shown) is applied over reinforcingline 72 so as to complete the formation of stabilizing layer 24.

B. Retention Assembly

Depicted in FIG. 10, a retention assembly 74 is positioned over form 22.Retention assembly 74 can be used either in conjunction with or insteadof reinforcing line 72. Retention assembly 74 comprises a network ofretention lines 94 that are interconnected at joints 96. Retention lines94 can be comprised of rope, webbing, plastic line, leather straps,wire, various forms of cable, and other types of flexible line havingsufficient tensile strength to withstand the tensile forces necessary torestrain pressurized inflation of form 22. That is, retention assembly74 is configured such that pressure within chamber 20 is increased, atleast a portion of the force produced by the pressure is carried byretention assembly 74. As a result, the pressure within chamber can beincreased without failure of form 22.

In one embodiment, retention lines 94 each have substantially the samelength and are formed into a polygonal pattern, such as a plurality ofhexagonal and pentagonal shaped polygons of equal length sides. Eachside of each polygon is common to an immediately adjacent polygon exceptfor the bottom most polygons adjacent to foundation 12.

In alternative embodiments, retention lines 94 can be disposed in anypattern that will achieve the objective of restraining inflated form 22.Various patterns for retention assembly 74 and techniques for connectingthe ends of the retention lines 94 are described in detail in U.S. Pat.No. 5,918,438. The specific disclosure within U.S. Pat. No. 5,918,438regarding alternative embodiments and methods for use and assembly ofthe retention assembly is hereby incorporated by reference.

VI. Reinforcing Mat

As depicted in FIG. 11, once stabilizing layer 24 is complete, areinforcing mat 98 is secured adjacent to interior surface 29 ofstabilizing layer 24. Reinforcing mat 98 typically comprisesinterconnected strands of conventional rebar. In the embodimentdepicted, reinforcing mat 98 comprises horizontally spaced apartvertical strands 97 that extend from footing 12 to the top of building10 and vertically spaced apart horizontal strands 99 that encirclebuilding structure 10. The various strands 97 and 99 are interconnectedusing conventional tying methods.

Reinforcing mat 98 is secured adjacent to stabilizing layer 24 usinghangers 58. That is, hanger rods 66 projecting out of stabilizing layer24 are bent around or otherwise used to secure reinforcing mat 98 inplace. Although mat 98 can be positioned directly adjacent tostabilizing layer 24, in one embodiment hangers 58 are used to supportreinforcing mate 98 at a spaced apart distance from stabilizing layer24. As a result, as will be discussed below in greater detail,reinforcing mat 98 is embedded within the support layer that is appliedthereon.

It is appreciated that depending on the size, configuration, and otherengineering requirements of building 10, rebar of one or more differentsizes can be used at different locations on building 10. Furthermore,the rebar can be positioned at one or more different spaces at differentlocations on building 10. For example, since the base of the building 10carries more weight, the rebar is typically larger and/or closertogether at the base of building 10 then at the top thereof. In yetother embodiments, it is appreciated that reinforcing mat 98 need not bemade of conventional rebar but can be made from other reinforcingmaterials such as metal cable, wire, mesh, and the like.

If desired, simultaneously with securing reinforcing mat 98 to hangers58 which are secured to stabilizing layer 24, additional hangers 58 canbe secured directly to reinforcing mat 98. These additional hangers 58are used for later suspension or mounting of an additional reinforcingmat 98. In addition, preconstructed frames, trusses, and other supportscan be placed at the previously marked door and window openings on form22 so as to provide reinforcing around these openings.

VII. Support Layer

As depicted in FIG. 12, once reinforcing mat 98 has been positioned, asupport layer 26 is formed so as to cover interior surface 29 ofstabilizing layer 24 and reinforcing mat 98. In this regard, reinforcingmat 98 functions as reinforcing for support layer 26. As support layer26 is built-up adjacent the footing 12, support layer will also coverreinforcing rods 31 projecting from footing 12, thereby fixing supportlayer 26 to footing 12.

Support layer 26 is typically comprised of a cementitious material. Asused in the specification and appended claims, the term “cementitiousmaterial” is intended to include any material that includes cement.Cementitious materials typically include graded sand and/or any numberof conventional additives such as fillers, fibers, hardeners, chemicaladditives or others with function to improve properties relating tostrength, finishing, spraying, curing, and the like. In one embodiment,the cementitious material comprises sprayable, commercially availablecementitious material such as “Gunite” or “Shotcrete”. Stabilizing layer24 can also be made of non-cementitious materials as long as theyprovide the required strength properties.

For efficiency, it is desirable that the material for support layer 26be sprayable. For example, the cementitious material can be appliedthrough a hose at high velocity which results in dense material having acured compressive strength in a range between about 3,000 psi to about10,000 psi. Alternatively, support layer 26 can be applied by hand, suchas by use of a trowel, or other techniques.

Support layer 26 may be formed as a single application layer or asmultiple overlapping sub-layers. For example, in one embodiment a firstsupport sub-layer is formed over stabilizing layer 24 prior to theattachment of reinforcing mat 98. Once first support sub-layer isformed, reinforcing mat 98 is formed thereon. A second support sub-layeris then applied over the first support sub-layer so as to embedreinforcing mat 98 therebetween.

The various sub-layers of support layer 26 can be comprised of the sameor different materials. Likewise, cementitious materials of differentgrade or properties can be used. Although not required, each successivesub-layer of support layer 26 is typically applied before the previoussub-layer is allowed to cure completely so as to effect maximum bondingbetween the successive sub-layers. The thickness of support layer 26 isin part dependent upon the size and configuration of building 10 andwhether other layers or support structures are to be added.

It will be appreciated that two or more support layers 26 may be formedin building structure 10 so that building 10 has sufficient structuralstrength. As shown in FIG. 13, two support layers 26 are shown having areinforcing mat 98 embedded in each support layer 26. As describedabove, additional hangers 58 can be secured in each support layer 26 tosecure subsequent reinforcing mats 98. It is appreciated that the typeof reinforcing mat 98 may differ between different support layers 26.Furthermore, the type of reinforcing mat 98 and number of support layers26 will vary depending on the engineering requirements of the particularbuilding structure 10.

As previously discussed, although not required, in one embodiment as thevarious layers or materials are added to building 10, the air pressurewithin chamber 20 is periodically increased so as to compensate for theload produced by the added weight. This increase in pressure can beaccomplished in one or more stages. Once all of the layers are appliedand cured to the extent necessary to provide the independent supportstrength, blower 57 is turned off and disconnected from building 10.

After completing building 10 thus far described, the various doorways,windows, and other openings can be cut through boundary wall 14.Inflatable form 22 may be removed from stabilizing layer 24 and aprotective coating such as asphalt and/or a suitable paint can beapplied over stabilizing layer 24 to protect it from moisture andultraviolet degradation caused by exposure to the sun. Inflatable form22 may then be reused. Alternatively, inflatable form 22 may be retainedon the completed building 10 and, if desired, coated to provideadditional protection to building 10. A further alternative is to removeform 22, apply a coating of cementitious material to the lower outerexposed portion of stabilizing layer 24 followed by a moisture barriercoating of asphalt over the entire structure and a final coating ofpaint for obtaining the desired appearance.

VIII. Ribs

In one embodiment as discussed above, building 10 can be formed bysimply completing the formation of one or more support layers 26. In analternative embodiment, particularly in vary large buildings, one ormore of the additional support layers 26 can be replaced with ribs. Asdepicted in FIG. 14, ribs 28 are formed on the interior surface of asupport layer 26. Ribs 28 increase the structural strength of building10 without adding the weight of an entire new support layer 26 withcorresponding reinforcing mat 98.

Ribs 28 are shown comprising spaced apart vertical ribs 28 a thatvertically extend from footing 12 to the top of building structure 10and spaced apart horizontal ribs 28 b that encircle building structure10. Vertical ribs 28 a and horizontal ribs 28 b integrally connect atjoints 140. In alternative embodiments, ribs 28 can be formed on supportlayer 26 in a variety of different interconnected or separated patterns.For example, ribs 28 can be configured in interconnected polygonalshapes having three, five, or more sides.

In one embodiment, as depicted in FIG. 15, building 10 havingreinforcing ribs 28 is produced by initially forming form 22,stabilizing layer 24, and one or more support layers 26 with reinforcingmat 98 embedded therein as previously discussed. Although notnecessarily required, reinforcing line 72 and/or retention assembly 74can also be used to enable selective increasing of the air pressurewithin chamber 20.

Once support layer 26 is formed, markings are made on interior surface35 thereof identifying the position for the plurality of ribs 28. A baselayer 100 is next formed that substantially extends the width and lengthof each rib 28. Base layer 100 is formed by initially mounting areinforcing mat 102 adjacent to the interior surface of support layer 26along the length of the rib. Reinforcing mat 102 comprises the samematerials and alternatives as previously discussed with regard toreinforcing mat 98 and is also held in position by hangers 58. Baselayer 100 in then applied over reinforcing mat 98. Base layer 100 istypically comprised of the same material and alternatives as previouslydiscussed with regard to support layer 26 and is generally acementitious material that is sprayed onto and over reinforcing mat 102.

Next, a foam core 106 comprised of a polymeric foam is formed on baselayer 100. In one embodiment, as depicted in FIGS. 15 and 16, foam core106 comprises a plurality of overlapping foam blocks 108 which aresecured to base layer 100 and to each other such as by an adhesive,hangers, and/or ties. Foam blocks 108 can be comprised of Styrofoam orother types of expanded foam or lightweight material. In one embodiment,foam core 106 has a substantially trapezoidal transverse cross section.In an alternative embodiment, the transverse cross section can betriangular, square, rectangular, irregular, or any other desiredconfiguration. It is appreciated that in alternative embodiment, baselayer 100 is not required and that foam core 106 can be mounted directlyon support layer 26.

As shown in FIG. 15, once foam core 106 is positioned on base layer 100,a reinforcing mat 107 is positioned along the length of each side offoam core 106 and transversely around foam core 106. Reinforcing mat 107is held against or slightly spaced apart from foam core 106 by hangers,ties, or other conventional fasteners mounted to core 106. Reinforcingmat 107 is also disposed adjacent to interior surface 35 of supportlayer 26 in the same fashion as if a second support layer 26 was beingformed.

Next, as depicted in FIG. 17, a finish layer 142 is applied overreinforcing mat 107 so as to cover foam core 106 and support layer 26.Reinforcing mat 107 is embedded within finish layer 142 so as to providereinforcing thereto. Finish layer 142 is typically comprised of the samematerial and alternatives as previously discussed with regard to supportlayer 26 and is generally a cementitious material that is sprayed. Ofcourse the size of rib 28 depends upon the engineered buildingparameters. In one embodiment, however, the completed ribs 28 have anexposed height H in a range between about 25 cm to about 125 cm.

It is appreciated that finish layer 142 can be applied in a variety ofdifferent acts and configurations. For example, a first finish layer cansimply be applied over foam core 106. A second finish layer can then beapplied over just the exposed portion of support layer 26 or over thecombination of support layer 26 and the first finish layer.

The arrangement and number of ribs 28 will vary depending on the size ofbuilding 10 and other conventional engineering parameters. Furthermore,it is appreciated that the spacing and size of ribs 28 can vary atdifferent locations on building 10. One of the benefits of using foamcore 106, as oppose to making ribs 28 completely out of cementitiousmaterial, is that ribs 28 can be relatively large which increases theirstructural effectiveness while minimizing their weight.

As with the other embodiments, as ribs 28 are built-up by successivelayers, the air pressure within chamber 22 can be increased to offsetthe added weight. In one embodiment, it is appreciated that the increasein pressure from inflation of form 22 to completion of building 10 canbe in a range between about 1-4 inches H₂O static pressure. This rangecan also be larger or smaller and depends on the parameters of building10. By making ribs 28 as light as possible, the air pressure increasewithin chamber 22 is minimized, thereby minimizing any risk of failureof form 22.

Turning now to FIG. 18, retention assembly 74 is used in associationwith the manufacture and positioning of reinforcing ribs 28.Specifically, as the radius of curvature of building 10 increases, thetop of building 10 become relatively flat, thereby, minimizing thestructural strength characteristics of the dome configuration at thatlocation. By using retention assembly 74 as previously discussed,inflated form 22 bulges out between spaced apart retention lines 94.This bulging out of form 22 causes form 22 to produce a plurality ofsmaller sub-domes 144 which are bounded between corresponding retentionlines 94. As subsequent stabilizing and support layers are applied, thelayers follow the same curvature as form 22. Accordingly, sub-domes 144can be used to provide multiple domed curvatures on the top of building10 which domed curvature increase the structural strength of building10.

Although not required, in the embodiment shown in FIG. 18, ribs 28 areplaces in complementary alignment with retention lines 94 of retentionassembly 74. In addition to the use of retention assembly 74, retainingline 72 can also be used as previously discussed.

FIGS. 19-21 show an alternative method for forming ribs 150 having afoam core 152. As shown in FIGS. 19 and 20, a plurality of elongatedforms 114 are secured on interior surface 35 of support layer 26 alongthe intended length for each rib 150. Forms are held in place usingconventional hangers or ties as previously discussed. If desired, baselayer 100 can be formed between forms 114 and support layer 26. Eachform 114 has an open sided substantially trapezoidal transverse crosssection. Specifically, form 114 comprises a pair of spaced apart planarside walls 116 that inwardly slope toward each other from a top end 117toward a bottom end 119. Each side wall 116 has an exterior surface 120and an interior surface 122. Side walls 116 are held in place by aplurality of brackets 124 mounted on exterior surface 120 of side walls116 and extending between side walls 116 at bottom end 119. (As with theother embodiments, depending on design parameters, either, both, orneither of retention assembly 74 and reinforcing lines 72 can be used.)

To minimize the weight of form 114, in one embodiment side walls 116 areformed of a light-weight, light-density material such as, but notlimited to, foam, styrofoam, plastic, corkboard, and the like.Alternatively, side walls 116 can be formed of any planer material suchas plywood or a sheet of metal. Brackets 124 can also be made of anymaterial, but in one embodiment are made of metal.

Bounded between side walls 116 is an open channel 126. In the embodimentdepicted, channel 126 is substantially open at both top end 117 andbottom end 119. As depicted in FIG. 21, once form 114 is secured to baselayer 100, channel 120 is filled with an polymeric foam, such aspolyurethane, so as to form foam core 152. In one embodiment, thepolymeric foam is simply sprayed into channel 126 through open bottomend 119. In an alternative embodiment, an end wall 154 depicted by thedashed lines in FIG. 19 extends between side walls 116 at bottom end119. In this configuration, end wall 154 closes off access to channel120 along bottom end 119. Polymeric form is then pumped into boundedchannel 120 through one or more openings formed on form 114 so as toform foam core 152.

Next, reinforcing mat 107 is secured adjacent to the exterior of form114 and support layer 26. Finish layer 142 is then applied over form 114and support layer 26 so as to embed reinforcing mat 107 therein andcomplete the formation of ribs 150. As previously discussed with otherembodiments, finish layer 142 can be applied over support layer 26 andform 114 in different steps and layers. As with the other embodiments,depending on design parameters, either, both, or neither of retentionassembly 74 and reinforcing lines 72 can also be used.

FIGS. 22-25 depict yet another method for forming alternative ribs 160having a foam core 162. As shown in FIG. 22, mounted on support layer 26at the location for each rib 160 is a form 164. Form 164 issubstantially identical to form 114 as previously discussed except thatside wall 116 are disposed in parallel alignment as opposed to aninwardly sloping alignment. In an alternative embodiment, however, oneor more of side walls 116 can also be sloping. Side walls 116 bound achannel 166 therebetween and are held in position by brackets 124. Inturn, form 164 is secured to support layer 26 using conventional ties orhangers. The components of form 164 can be made of the same materialsand alternatives as discussed with form 114. The size and positioning ofchannels 166 depends on the engineering parameters for building 10. Inone embodiment, however, channel 166 typically has a width in a rangebetween about 15 cm to about 60 cm and a depth in a range between about10 cm to about 125 cm.

As depicted in FIG. 23, a longitudinally extending shoulder 168 having asubstantially triangular transverse cross section is formed at theintersection of the exterior surface 120 of each side wall 116 andsupport layer 26. Each should 168 has an exposed transition surface 170that extends at a slope from bottom end 119 of side wall 116 to supportlayer 26. It is noted that were adjacent ribs 160 are being formed,shoulders 168 are spaced apart so that a portion 172 of support layer 26remains exposed between adjacent shoulders 168. In one embodiment,shoulders 168 are formed by spraying on a polymeric foam such aspolyurethane foam. Alternatively, shoulders 168 can be formed of one ormore blocks of foam or other light weight material that are secured inplace using conventional methods such as adhesive, ties, and/or hangers.

Turning now to FIG. 24, one or more spaced apart layers of reinforcingmat 172 are next positioned within channel 166. Channel 166 is thenfilled with a cementitious material so as to form an elongated strut 174having a substantially square or rectangular transverse cross section.It is appreciated that reinforcing mat 172 and the cementitious materialcan be positioned in one or more applications or layers.

As depicted in FIG. 25, once strut 174 is formed, a reinforcing mat 176is positioned adjacent to strut 174, shoulders 168, and portion 172 ofsupport layer 26. A finish layer 178 is then applied over reinforcingmat 176 so as to complete the formation of ribs 160. It is appreciatedthat completed ribs 160 comprise a substantially I-beam portion whichincludes strut 174 extending between support layer 26 and finish layer178. This I-beam configuration adds increased structural strength toboundary wall 14 of building 10. At the same time, ribs 160 comprise twofoam cores, i.e, shoulders 168 and, where applicable, side walls 116,which minimize the weight ribs 160.

IIX. Completed Building

Once the ribs are formed and sufficiently cured, the pressure withinchamber 22 can be released and both the interior and exterior ofbuilding 10 completed as previously discussed above in section VII.Building 10, while being illustrated as a circular dome shapedstructure, may take alternative configurations such as a barrel shellshape, an elliptical shape, a rectangular shape, or any other desiredconfiguration. Alternatively, as depicted in FIG. 26, a building 180configured having compound curves, i.e., a “caterpillar” shape). Themethods of construction in accordance with the present inventionfacilitate the construction of buildings of substantial size. Forexample, the illustrated domed building structure 10 may have a basediameter in a range from about 30 meters to about 350 meters.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. For example, anumber of methods and alternative structures and disclosed herein. It isappreciated that features of different methods and structures can bemixed and matched to form new methods and structures. As such, thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

1. A method of forming a building comprising: inflating an inflatableform such that a chamber bounded by an interior surface of theinflatable form has a first air pressure that supports the inflatableform; applying a stabilizing layer comprised of a polymeric foam on theinterior surface of the inflatable form, the stabilizing layer havingreinforcing line at least partially embedded therein; positioning atleast one support layer comprised of a cementitious material on aninterior surface of stabilizing layer; and increasing the air pressurewithin the chamber at some time after applying the stabilizing layer,the reinforcing line being at least partially embedded within thestabilizing layer so that tension on the reinforcing line is increasedas the air pressure is increased within the chamber, whereby at least aportion of the load applied by the increased air pressure is absorbed bythe reinforcing line.
 2. The method as recited in claim 1, wherein theinflatable form is inflated without mechanically constraining anexterior surface of the inflatable form.
 3. The method as recited inclaim 1, further comprising applying retention line over an exteriorsurface of the inflatable form so as to restrain expansion of theinflatable form.
 4. The method as recited in claim 1, wherein thepolymeric foam is sprayed onto the interior surface of the inflatableform.
 5. The method as recited in claim 1, wherein the step of applyingthe stabilizing layer comprises: spraying a first layer of polymericfoam onto the interior surface of the inflatable form; securing thereinforcing line along an interior surface of the first layer ofpolymeric foam; and spraying a second layer of polymeric foam onto theinterior surface of the first layer of polymeric so as to at leastpartially embed the reinforcing line within the polymeric foam.
 6. Themethod as recited in claim 5, further comprising tensioning thereinforcing line along the length thereof after or while securing thereinforcing line to the first layer of polymeric foam but prior tospraying the second layer of polymeric foam.
 7. The method as recited inclaim 1, further comprising mechanically connecting the reinforcing lineto the stabilizing layer at at least two spaced apart locations alongthe reinforcing line.
 8. The method as recited in claim 1, wherein thesupport layer is sprayed onto the interior surface of the stabilizinglayer.
 9. The method as recited in claim 1, further comprising a forminga rib on the interior surface of the at least one support layer.
 10. Themethod as recited in claim 1, further comprising: forming a corecomprised of polymeric foam directly on or inwardly spaced from theinterior surface of the at least one support layer; and applying a layerof cementitious material over the core so as to form a rib.
 11. Themethod as recited in claim 1, further comprising: forming a first coreand a spaced apart second core on the interior surface of the at leastone support layer, the first core and second core being comprised of apolymeric foam; producing a strut comprised of cementitious materialbetween the first core and the second core; and applying a layer ofcementitious material over the first core, second core, and strut.
 12. Amethod of forming a building comprising: inflating an inflatable formhaving an interior surface; applying a stabilizing layer comprised of apolymeric foam on the interior surface of the inflatable form;positioning at least one support layer comprised of a cementitiousmaterial on an interior surface of stabilizing layer; and forming a ribon the interior surface of the at least one support layer, the ribcomprising: a core comprised of a polymeric foam; and a layer ofcementitious material disposed over the core.
 13. The method as recitedin claim 12, wherein the inflatable form is inflated withoutmechanically constraining an exterior surface of the inflatable form.14. The method as recited in claim 12, further comprising applyingretention line over an exterior surface of the inflatable form so as torestrain expansion of the inflatable form.
 15. The method as recited inclaim 12, wherein the step of applying the stabilizing layer comprises:spraying a first layer of polymeric foam onto the interior surface ofthe inflatable form; securing a reinforcing line along an interiorsurface of the first layer of polymeric foam; and spraying a secondlayer of polymeric foam onto the interior surface of the first layer ofpolymeric so as to at least partially embed the reinforcing line withinthe polymeric foam.
 16. The method as recited in claim 15, furthercomprising tensioning the reinforcing line along the length thereofafter or while securing the reinforcing line to the first layer ofpolymeric foam but prior to spraying the second layer of polymeric foam.17. The method as recited in claim 15, further comprising mechanicallyconnecting the reinforcing line to the stabilizing layer at at least twospaced apart locations along the reinforcing line.
 18. The method asrecited in claim 12, wherein the support layer is sprayed onto theinterior surface of the stabilizing layer.
 19. The method as recited inclaim 12, further comprising: forming a core comprised of polymeric foamdirectly on or inwardly spaced from the interior surface of the at leastone support layer; and rib. applying a layer of cementitious materialover the core so as to form a
 20. The method as recited in claim 12,further comprising: forming a first core and a spaced apart second coreon the interior surface of the at least one support layer, the firstcore and second core being comprised of a polymeric foam; producing astrut comprised of cementitious material between the first core and thesecond core; and applying the layer of cementitious material over thefirst core, second core, and strut.